14 MIDDLEM1SS: GEOLOGY OF HAZARA AND BLACK MOUNTAIN. 



ground between the older slates and the enfolded secondary rocks ; 

 each is quite distinct, and the necessity mentioned by him for colouring 

 as palaeozoic these large areas, although they contain folds of secondary 

 rocks, is a mechanical one, due to the small scale of the Manual map 

 relative to the sharp flexuring of the country. I wish to draw atten- 

 tion to this point somewhat closely, because Mr. Oldham's language 

 leaves a faint suspicion behind that the occurrence of these enfolded 

 secondary rocks might perhaps after all give the index to the true 

 age of the enfolding slates, which may, therefore, themselves be 

 secondary. This, however, in Hazara certainly, is far from being 

 the case ; the Slate series is one thing, and the fossiliferous rocks 

 are another, quite distinct and separable, on a large-scale map, the 

 one from the other. 1 



This absence of fossils in the Slate series does not seem to be 

 owing to the fact that the rock has been cleaved to such an extra- 

 ordinary extent as to have obliterated all traces of life, for many of 

 the interbedded fine dark quartzites and grits shew no profound 

 deformation of their grains, but on the contrary evince all the ordinary 

 characteristics of a sedimentary rock that has accumulated most 

 probably at the bottom of a tranquil sea. Nor for the matter of that is 

 it at all a recognised fact that cleavage alone can completely obli- 

 terate all traces of organisms in a rock. It is well known to be able 

 to distort and deform fossil remains, to draw them out in one or two 

 directions, and to flatten them in another, but that it can altogether 

 destroy them without leaving a trace over so great an area and 

 through so great a thickness as the Slate series commands is, I think, 

 not proved. 



Under these circumstances it is a little difficult to assign to this 



great series a definite stratigraphical position, 



Ageandstratigraphi- or t correlate it as regards age with standard 

 cal position. ° «=> 



palaeontological horizons; and in order to do so, 



even approximately, we must use the indirect methods of reasoning 



which belong to comparative geology. 



1 That this was Wynne's matured belief, see Rec. G. S. of I., Vol. XII, p. 121. 



14 ) 



